4.0 ohv coolant contamination/loss

[cp2295]

Well the heads warped bad and all the exhaust valves are leaking! Good to know. Gonna have both heads gone thru by the machinist


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[RonD]

You dodged a bullet if head isn't cracked, warped just needs to be surface hopefully.

 

[cp2295]

Nope got a call back and the machinist said the head is cracked big time between the valve seats, about 3/4" deep so I purchased the j&c heads off eBay for $400, come with new valves and everything, just gonna replace both heads and call it good.


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[cp2295]

Hey so just curious since I have the motor apart I wanted to fix another issue I have. So when the trucks under light load at or above 2500rpms while In gear it makes a rattle. Not a knock, but a valve train rattle or even like a timing chain? It hasn't gotten any worse over 20k miles. It doesn't do it when the motor is cold. When I start it up in the morning it'll make the noise then go away almost instantly. When it's hot and I restart it the truck won't make the rattle noise. Another time it makes the rattling is when I shift gears.

It won't make the rattling below 2500rpms, and it won't make it in neutral (I've gotten it to before but rarely) it won't make the noise when I'm on the gas good, but as soon as I go to shift it'll do it.

It's hard to describe, never had a vehicle do it before. When I had the motor apart when I swapped it in the timing chain felt good with no play and the tensioner look good. The rods all looked nice and so did the mains, tho I never checked the clearances.

What's your thoughts guys? No one seems to know what it is. It couldn't be lifters could it? It makes a very slight lifter tick at idle, and I'm not very concerned about it, I see the pushrods have some slight galling. There is no knocking, it does make the marbling noise at idle that all these 98-00 4.0s make.


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[cp2295]

Well I pulled the motor and found all the rod journals are scored. Probably had low oil pressure and couldn't keep the lifters filled so they rattled with light load on them. Insane how this motor ran fine yet had huge issues, cracked and warped heads, leaking valves, badly scored rod journals, and it purred.. Stout motor!! Gonna go all out with a rebuold


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